Things that make you go "Hmmmm…"

[Uncwilly]

Originally Posted by Dubslow

On the mountain? Nice!

Yes, about the same elevation as the Hollywood sign. Got to see much of the looping around. Looking down on all of the folks at the Observatory was fun. It was quite hot, the fire department rescued a person off of a ridge (they had heat stroke) by helicopter and treated many others.

[LaurV]

Originally Posted by LaurV

[edit: about metronomes. (few cross-posts in the same time)]

Scrap that! It seems like my brain is too much damaged by production issues... When I watched the video I was thinking to metronomes which are "required" (by customer specification) to beat synchronous (no idea for what, for teaching music in a class, whatever he needs them for, not my business) and I was convinced that what I see in the movie is the factory QA line testing those metronomes before shipping them out... That is why I wondered what technical solution they adopted to make them beating together, and somehow I was thinking they need too much time for it - I could make them going synchronous much faster/sooner.

Meantime I have read the English description linked. That is different story, and sounds even more interesting...

But I am still laughing like an idiot around minute 2:05, I don't know why, I can't stop it!

[Dubslow]

Originally Posted by LaurV

But I am still laughing like an idiot after minute 2:05, I don't know why, I can't stop it!

Both of the top comments are about it being a hipster and needing to control one's OCD impulses...

[Dubslow]

Perhaps this better belongs in the silly links thread... depends on your point of view.

http://spikedmath.com/math-games/

[kladner]

This is really beautiful.

http://hint.fm/wind/

[kladner]

i sent the metronome piece around to a bunch of people. One of my cousins responded with speculations about the period of the support surface.

Impressive demo. Interestingly, of the 32 metronomes, there's one holdout that stays 180º out of phase until late in the game.

If you click through to the original YouTube post, it bears a Japanese caption which Google Translate renders, not too badly I suspect, as:

When you move the metronome and put on a table that moves multiple metronome that ticks all the metronome sound at the same time as it is known in sync eventually.

Close enough. My guess is that it said:

When you start a metronome and put it on a movable table with multiple ticking metronomes, eventually all the metronomes sound at the same time ("in sync").

If you look closely you can see the alluded-to movable support scheme for the rear corners of the styrofoam platform - a suspension wire at each corner so that the whole table is a pendulum, with wires that appear to be about a foot long judging by the front crossbeam (rear one's up out of view). For what it's worth, I get that this should give a natural frequency for the table (1 / 2pi ) * sqrt (g/l) of about 0.9 hz whereas I time the metronomes at 1.33 hz. Wouldn't want 'em matched to table frequency, I suspect -- table might go nuts, or else conceivably (rusty on this) might exactly track the metronome bobs so their swing angle became zero and they'd cease to tick...


If the metronomes weren't powered, I'd expect them to act as a Vibration Eliminator to kill the swing of the table -- but with them being the energy source.... FWIW as set up in the video the table swings in opposition to the metronome bobs.

He says it is OK to post this part of his message. I am just curious if any of the math/science people want to take up the question of what would happen if the swinging support matched the metronomes' timing.

[Xyzzy]

We wonder how close each metronome has to be to the others (in Hz) for this to work.

We wish we worked in that lab!

[kladner]

Good question. I had supposed that they were set nominally the same, and that phase differences were the meat of the matter.

[Xyzzy]

http://arstechnica.com/information-t...network-havoc/

[Dubslow]

http://www.aero-news.net/index.cfm?d...a-8658835f4abd

[kladner]

Originally Posted by kladner

Good question. I had supposed that they were set nominally the same, and that phase differences were the meat of the matter.

Someone on my cousin's mailing list responded that this experiment only worked because the metronomes are Japanese. If they were American they would still be out of step.